For high schools that the colleges know, grades are always taken in context of the school. Our kids high school didn't have ranks, but until recently did have grade distributions. Most years, only 2% achieved more than a 4.5 weighted GPA. The maximum possible GPA is 5.0, which requires having every class be an honors or AP class, and getting an A+ in that class.

A 4.5 was achievable by taking all honors/AP classes and getting an A- in every class. There was a very high overlap overlap between getting into that top 2% and getting into a top 10 college. So students needed to be strong relative to others, but not perfect.